American Railroads and Carbon Footprints

For going on two centuries, the railroads of America have relied almost exclusively on fuels that, when burned, release forms of carbon into the environment. The “almost” exception is for electric railroads, but not for all electric railroads. The exceptions must use only solar, wind, hydroelectric, nuclear, or fuel cell power to the exclusion of power plants that burn the same kinds of fuels that, in a locomotive, release carbon.

At the beginning of the environmental awareness that has become a driving force of American politics and business, the focus was on the generation or emission of hydrocarbons. Hydrocarbons are a gross category of chemicals made up of only hydrogen and carbon atoms, including many products of crude oil and natural gas, while the emissions are those compounds left over when an internal or external combustion engine incompletely burns those original hydrocarbons.

In the days of steam locomotives (roughly the 1830s to 1960), coal, oil, or wood was relatively inefficiently burned in a boiler to produce steam, which drove the actual steam engine that turned the wheels of the locomotive. The unburned fuel was ejected from the stack, either by draft, mechanical blower, or the action of steam exhausted from the engine, and into the air. The smoky emissions consisted of steam, soot, ash, and hydrocarbons, but the focus then was on soot, with numerous municipalities enacting smoke ordinances that could only be enforced using ground observers that measured the color and opacity of the smoke.

Many electric locomotives were contemporary with steam locomotives after the turn of the 20th century. The wires and third rails from which the locomotives drew power were energized, for the most part, by generators turned by turbines or engines. The steam to turn the turbines was made, mostly, in boilers heated by coal. In areas where water power was feasible, the turbines were in hydroelectric dam installations. While the hydroelectric installations were without hydrocarbon emissions, the steam boilers had (and have) the same kinds of emissions as steam engines.

The advent of the diesel brought internal combustion to railroad locomotives in a big way. From the late 1930s to the late 1950s, most railroads either dieselized or stayed with electrified lines. Most diesels burned a specialized kind of refined petroleum, and still do, though they can and do burn other oils and even gasoline. Early diesel emissions were also sooty, but the ash problem went away. However, diesels emitted more complex hydrocarbons.

It should be noted that coal ash and soot and diesel hydrocarbon emissions also include metal oxides, hydrides, and nitrogen oxides. Sounds dirty, doesn’t it?

Here is a good place to pause and give a simple example of what combustion is. Burning the simplest form of carbon fuel, CH4, or methane, results in the combination of two units of oxygen, O2, with one of methane to produce heat, two units of water, and one of carbon dioxide, the latter being the dreaded greenhouse gas that spawned the term “carbon footprint” at the beginning of the 21st century. Burning more complex fuels, those with multiple atoms of carbon and hydrogen and other compounds bound together, still, if burned efficiently, produce mostly heat, carbon dioxide, and water vapor. Your body, the most efficient heat engine ever devised, burns the food you eat and combines it with the air you inhale to produce the energy that runs your body, letting you exhale carbon dioxide and water vapor. It’s why your breath will fog a mirror.

Sometime during the late 1990s, the environmental movement realized that it had done a lot over the past fifty years or so to throttle the emission of hydrocarbons and oxides of nitrogen, and it turned to the naturally occurring CO2 as the next culprit. HCs, NOxs, and soot caused smog, acid rain, dirt, and a multitude of respiratory maladies we who were alive then remember from the 50s, 60s, and 70s. But carbon dioxide caused a greenhouse effect that is alleged by science to warm our planet. The greenhouse effect is real, but whether the planet is naturally regulated enough to balance this effect is still a topic of debate, or should be.

So, your carbon footprint, the railroads’ carbon footprint, is really the amount of carbon dioxide emitted. It’s a carbon dioxide footprint.

The word footprint is used, I think, because of its negative emotional response. A footprint is something bad, or at least worthy of guilt. “Don’t track footprints on my new carpet.” “Don’t leave footprints on an unspoiled landscape.” Ad infinitum. I think they should have used “tire tracks,” myself, as in, “The Hazzard brothers left tire tracks on my cornfield.”

Over the past two decades, diesel locomotive emissions have been reduced by the manufacturers until they are very clean. This is not without cost. The same is true of automobiles, of course, and the same technologies that are beginning to power private passenger cars are also starting to power locomotives. Railroad “bigness” has an advantage in some of these so-called green technologies. For instance, it’s far easier to accommodate fuel cells in locomotives. Even nuclear power, such as the power plants aboard some space satellites, could be fit in. So far, it hasn't been possible to put enough solar panels on a locomotive to make it pull anything more than itself; but early steam had the same problem.

None of this means that internal combustion engines have stopped emitting carbon dioxide. It’s just not possible to burn the compounds we normally consider as fuels without doing so. The exception is pure hydrogen, which burns to produce only water. Hydrogen fuels may be a solution, but are dangerous to handle. (Many things burn, or combine with oxygen to produce heat, without making CO2, but most are not economic or otherwise clean fuels.) Production methods for exotic fuels, like hydrogen, are not without their own carbon footprints.

Sans the wholesale electrification of North American railroads along with the wholesale conversion of electric generation to green sources (nuclear, solar, wind, water—each of which have their own negative emissions and small carbon footprints), railroads have, and will continue to have, a carbon footprint for years or decades to come.

Railroads are better than they were in the 1940s, even than they were in the 1980s. But if good only means zero carbon footprint, then for you and me, and for the railroads, it isn’t going to happen soon.

©2017 – C. A. Turek – mistertrains@gmail.com

(Charles A. Turek is a writer and novelist based in Albuquerque, NM. After four decades working in areas of the insurance industry related to transportation, he now writes on all aspects of American railroading. Charles is a political conservative but believes in public funding of passenger rail as a part of the federal government’s constitutionally conservative obligation to provide for defense and public infrastructure so that private enterprise may flourish.)